PR c/17807
	* c-decl.c (undef_nested_function): New variable.
	(pop_scope): Diagnose undefined nested functions.
	(finish_function): Don't attempt cgraph processing or genericizing
	if current top-level function contained an undefined nested
	function.  Reset undef_nested_function at the end of a top-level
	function.

testsuite:
	* gcc.dg/nested-func-3.c: New test.
	* gcc.dg/pr18596-3.c: Expect error for undefined nested function.

From-SVN: r94645